The present invention relates to a coaxial cable and its manufacturing method. For example, the invention relates to a coaxial cable capable of connecting coaxial cables directly to, for example, interconnections provided on a substrate without intervention of a connector, as well as to its manufacturing method.
An electric connector for connecting plural coaxial cables to interconnections on a substrate is known (refer to Patent document 1, for example).
As shown in FIG. 9, this electric connector 100, which is to connect coaxial cables 101 electrically to a receptacle (not shown) by fitting the former into the latter, is provided with an insulator housing 102 made of a synthetic resin such as plastics, plural conductive terminals 103 which are arranged at a prescribed pitch in the width direction of the housing 102, and a shield plate 104 which covers the housing 102 from above. The conductive terminals 103 are positioned with respect to and placed in housing recesses 105 which are formed at a prescribed pitch adjacent to each other in the width direction of the housing 102. Each coaxial cable 101 to be connected to a conductive terminal 103 is composed of a center conductor 107 to be connected to the conductive terminal 103 with solder or the like, an insulator 108 which surrounds the center conductor 107, an outer conductor 109 which surrounds the insulator 108, and an outer sheath 110 which surrounds the outer conductor 109. The center conductors 107 of the coaxial cables 101 are connected to the corresponding conductive terminals 103, respectively, and the outer conductors 109 are connected together by means of a caulking member 111.
[Patent document 1] JP-A-2005-302604
Incidentally, in a coaxial cable used in a cell phone or the like, cables are connected to other cables or a substrate or the like via an electric connector. In the electric connector 100 disclosed in the above-mentioned Patent document 1, the outer conductors 109 of plural coaxial cables 101 are caulking-connected together by means of the caulking member 111 which is a single, common connection metal plate without being soldered. With this measure, the bendability of the coaxial cables 101 is not lowered due to solder impregnation into the outer conductors 109, as a result of which the cables 101 are improved in the workability in a narrow connection space.
However, as apparatus are reduced in size, connection spaces are becoming increasingly narrower and cables are being reduced in diameter (e.g., AWG (American wire gauge) #40 to #46). In these circumstances, it is difficult to connect the center conductors, arranged at a small pitch, of a coaxial flat cable to an electric connector as disclosed in the above-mentioned Patent document 1 or the connection terminals of a substrate or the like. Furthermore, the connection using the caulking member 111 which is disclosed in Patent document 1 has a problem that the fixing strength of the cables 101 (outer conductors 109) is insufficient.
It is therefore desired to realize connectorless connection in which, for example, to minimize the number of connection positions, a connector is not used and the center conductors of respective cables are connected directly to a circuit of an apparatus.